The invention relates to a fuel injection apparatus for internal combustion engines. The apparatus includes a control apparatus which produces an uncorrected injection pulse, in accordance, for example, with the aspirated air quantity per stroke, for the controlling of at least one injection valve of the engine. The apparatus also includes a correction frequency generator, for modulating the injection pulse for the injection valve, in accordance with the various operational parameters of the combustion engine.
Digital control apparatuses for fuel injection systems are capable of computing the injection time during which fuel is supplied to the cylinders of the internal combustion engine via electromagnetic injection valves, that is of computing the duration of the electrical pulses delivered to the injection vlaves. The duration is computed from the basic data regarding the air quantity aspirated by the internal combustion engine, and from crankshaft rpm. A so-called uncorrected injection pulse is formed from these basic data. This uncorrected injection pulse is still dependent upon further operational parameters of the internal combustion engine, for example, temperature. It is, moreover, still not attuned to the various conditions present, for example, during idling, partial load operation, and full load operation. This attuning to the cited and to other operational parameters is accomplished with a correction apparatus, which adjusts, to a geeater or lesser extent, the uncorrected injection pulse in accordance with the given operational parameters. The corrected injection pulse is commonly still further processed by a correcting circuit for a battery voltage dependent compensation of the injection pulses. Subsequent thereto, the injection pulses are delivered in their final form to the injection valves of the internal combustion engine via the distribution and amplifier stages, where they determine the injection time, i.e., the fuel quantity to be injected per stroke.